I want to use my Nucleo-F303RE to develop firmware for a USB HID.

The stm32f303ve data sheet states in section 3.25 that for the USB peripheral to work, the MCU needs a HSE crystal oscillator.

According to the user manual UM1724 section 6.7.1, the board has a fixed 8Mhz clock from the ST-Link MCO (which, in turn, has a 8Mhz crystal installed). I'm hoping to be able to use that clock for the USB device. Is it sufficient or will I have to get the parts to populate the X3 position?


1 Answer 1


The 8Mhz clock from the ST-Link processor will work the same as an 8Mhz HSE crystal oscillator.

As long as you set the internal clock routing, PLL and clock dividers correctly to generate the required internal USB clock, you will not need to add an HSE crystal to use USB.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.